By determining how many of those molecules to hold onto, how many to keep in the body, how many to release determines the internal composition with regard to that ion.

通过控制体内这些分子的水平,即体内保有多少,又排出多少,就能够保证内环境中离子组成的稳定

耶鲁公开课 - 生物医学工程探索课程节选